World S
Successfully complete World 6. World S will be available after the ending sequence.

Grandmaster Galaxy
Collect 120 gold stars and 120 green stars to unlock the Grandmaster Galaxy in World S. This is a 2D level with a Comet Medal and a one star to collect.

Co-Op mode sound effects
Press Up, Down, Left, or Right on controller two to make sound effects on player one's Wiimote. Press Minus, Plus, 1, and 2 on controller one to make sound effects on player two's Wiimote.

Play as Luigi
* Collect The Flotacious Blimp Fruit star in the Tall Trunk Galaxy. You can now talk to Luigi at the beginning of certain levels to control him.
* To play as Luigi in any level, defeat Bowser at Bowser's Galaxy Generator. Then, check the Mail Toad. You should receive a message from him. Enter the "L" on the spaceship to switch to Luigi.

All Luigi ghosts
Collect 9,999 to unlock all the Luigi ghosts without having to complete each level as Luigi.

Time trial developer ghosts
Successfully complete a level as Luigi. A "ghost" of developers completing that level will become unlocked, for you to beat.

Green stars
Successfully complete the game with 120 gold stars to be able to collect 120 green stars.

Saved game profile icons
* Collect 120 stars to mark that saved game profile with a silver crown.
* Collect 240 stars to mark that saved game profile with a gold crown.
* Collect 242 stars and become the "Master of Galaxies" to mark that saved game profile with a platinum and jewel crown.
* Collect all 120 Power Stars and defeat Bowser again to mark that saved game profile with a Rosalina icon.

Death counter
Collect the final star in The Grandmaster Galaxy (The Perfect Run) to see the number of deaths you have accumulated on your saved game file.
Watermelons instead of coconuts

Easy lives
Use the following trick to get 99 lives with two players. In World 4, enter the Supermassive Galaxy. You will eventually reach three turtles walking around in a circle. Take the Spin Drill and kill all but one of the turtles. Have the player two hold the last remaining turtle. Have player one run and jump on the turtle's back from behind it. Stay on the turtle. You do not have to do anything (such as pressing A as soon as you get on its back); Mario will jump anyway. Use the Wiimote to stay on its back so you do not jump off. You will get 99 lives from this, but they will not be saved after you turn off the game. This trick must be repeated to get the lives back.

Longer jumps
Get a running start then do a triple jump. As soon as you land, do a long jump to get twice as far. Note: This will be easier to do if there are no gaps to avoid.

Flipping high dive
Get to a location that is high above deep water, for example at Starshine Beach Galaxy. Run up the small sandy incline at the beginning. Search for a wooden plank hanging off a side. Have Mario move to the edge and he will look down at the water. Turn around while standing there, then hold Nunchuk Z and press Jump to perform a flipping back flip dive,

Defeating the Boomerang Bros.
Press Z to crouch to avoid their boomerangs. Walk over to the Boomerang Bros. while crouched, then spin to kill them.

Luigi gives out Star Bits
If you see Luigi at the beginning of a galaxy, have player two point him and press A. Then, have player two spin to make Luigi give out Star Bits.

Die during the credits
Collect a Bee Mushroom during the credits and wait for the Shiverburn area to start. When the page flips, fly toward the screen before you appear. If done correctly, you should die by falling. The screen will turn black while the sound effects from the credits play. At the end, it will read "THE END" with "TOO BAD" in the background.